1. Field of the Invention
The present invention relates an additive for improving the properties of nail varnishes, to a process for producing such an additive, and to its use in nail varnishes.
2. Discussion of the Background
A modern nail varnish serves to maintain and convey a pleasing shape and colouration of fingernails and toenails. Additionally, the nail is protected against environmental influences and gains high hardness. Special efforts are undertaken to make applied nail varnishes long-lasting, scratch-resistant, splinterproof, in an attractive colour and pleasing lustre.
Current nail varnishes comprise a large number of ingredients. The most important representatives of these include the film formers, adhesion promoters, plasticizers, solvents and pigments. Fumed silicas are used for modifying the rheology and thixotropy. Despite this wide possibility of formulating very good varnishes, the shelf-life, hardness and scratch resistance are still unsatisfactory.
Even nowadays the primary film former used is still primarily nitrocellulose, which essentially ensures good hardness and toughness of the varnish surface. However, as is disclosed in DE 32 43 291 A1, further resins generally have to be added in order to reduce fracture and chipping.
U.S. Pat. No. 4,873,077, GB 1177420 and DE 69111621 disclose various additives for improving the wear resistance, combating splitting of the nail, avoiding cracking, chipping and fracture in the form of synthetic, natural and mineral fibres.
In the specification DE 4334938 A1, alkyl-branched and polyglycol-ether-containing fatty acid esters are recommended for rapid drying with hard and more scratch-resistant films.
For improving the external appearance, the application DE 198 22 722 A1 discloses inorganic-organic hybrid polymers which can be added to a nail varnish formulation. These are organofunctional silanes which carry three condensable and hydrolysable functions on the silicon atom, and also have a crosslinkable organic radical in the molecule. 40 to 50° C. are specified as particularly preferred drying temperatures. The drying time should be 2 to 20 min.
Copolymers of acrylates and methacrylates, disclosed in FR 7614430, and copolymers with polar functions, disclosed in DE 31 12 888 C2 are said to reduce brittleness of the dried nail varnish and improve its adhesion to the nail.
It is common to all these specifications that, to improve the properties of nail varnishes, a large number of substances is added to them which are admixed to the finished cosmetic product in an expensive process. In view of the sensitivity of the consumer towards side-effects, which has been increasing for a long time, it must also be observed that the customer will refrain completely from the use of nail varnishes if he has to reckon with allergy-triggering effects due to the admixed acrylate monomers in accordance with the background art.